Wireless communication systems are sometimes allocated shared or overlapping frequency bands. Overlapping allocations of this sort may cause interference from one communication system to another. For example, a terrestrial cellular system may cause interference to satellite communication receivers that operate in overlapping channels.
Various methods and systems for mitigating interference are known in the art. For example, U.S. Patent Application Publication 2002/0110206, whose disclosure is incorporated herein by reference, describes a combined interference cancellation communication system for satellite communications. A receiver receives a waveform having data information and noise information. A filter bank is coupled with the receiver to receive and filter waveform and output channel information received by the receiver. A demodulator provides an estimation signal representative of an estimation of at least one parameter of the channel information. Soft-input and soft-output decoders are provided to receive the channel information in order to calculate and estimate interference values based on the estimation signal. A soft-input and soft-output interference canceller receives the output channel information and the estimated interference value calculated from the decoders in order to provide a data signal substantially without interference.
U.S. Patent Application Publications 2004/0042569 and 2007/0098121, whose disclosures are incorporated herein by reference, describe an interference signal canceling system for canceling interference signals from earth station received signals using a two input adaptive cancellation network. Main and auxiliary signals are derived directly or by coherent conversion to intermediate frequency using an auxiliary antenna, cross-polarized feed, or auxiliary squinted feed. Filters set receive and canceling bands. Cancellation combines the main signal with a phase, amplitude and time modulated sample of the auxiliary signal. A receiver correlates the auxiliary signal with a sample of the combined output to minimize interference.
U.S. Patent Application Publication 2009/0102706, whose disclosure is incorporated herein by reference, describes a satellite interference canceling system that cancels interference between two or more signals received by a satellite receiver. Gain and phase are applied to the received signals and then combined with the other signals to result in cancellation by subtraction. The gain and phase values needed to cancel the interference are derived from measurements of Carrier-to-Noise ratio (C/N) as an indication of the interference level.
U.S. Pat. No. 6,597,750, whose disclosure is incorporated herein by reference, describes a system for receiving multiple broadcast channels transmitted with different polarizations. The system includes a first demodulator for demodulating a first channel having a first polarization to produce a first demodulated channel signal, and a second demodulator for demodulating a second channel having a second polarization, opposite to the first polarization, to produce a second demodulated channel signal. An adaptive interference cancellation network, coupled to the first and second demodulators, cancels interference, derived from the second channel, in the first demodulated channel signal to produce a received signal.
Verdú describes successive interference cancellation processes, in “Multiuser Detection,” Cambridge University Press, November, 1998, chapter 7, which is incorporated herein by reference.